Tuning 5.3 Chevelle, no power.
07-20-2016, 05:11 PM
#1
Restricted User
Thread Starter
Tuning 5.3 Chevelle, no power. When I first fired up this Chevelle, it had loads of power. Wheel spinning power.
Now, it won't spin the tires if you hammer it from a 5 MPH roll in first.
Setup is:
05 5.3
706 heads
Truck intake
DBC, stock throttle body.
MAF tune.
PAC 1218 Springs
226/232 .580/.590 115 LSA cam.
TH350
1 3/4" Long tubes
2.25 dual exhaust with flowmasters.
2800 stall truck converter that seems to be stalling around 2200.
99 4.8 ECU flashed for 1 bar OS MAF Enhanced tune.
TR5 plugs gapped at .040
There are some oddball situations here.
1. After the first fire, we swapped from the 99 4.8 21.8 lb/hr injectors to the 5.3s 25 lb/hr injectors after hitting 100% duty cycle. I have NOT updated the injector data.
2. I'm tuning without a wideband. I removed 30% fuel on Primary/Secondary VE tables from 0-800 RPM, 20% fuel from 1200-1600 RPM, 12% fuel at 2000 RPM. Added 10% at 3200, 15% at 3600-4200, 20% at 4600-5000, and 25% fuel from 5000+. This made it idle and cruise very well. I just need it 'close' for the time begin. It was originally started/tuned without the MAF plugged in.
3. I had to disable STFT/LTFT because it kept adding 50% to Bank 2. There is an exhaust leak between the header and exhaust.
4. I used the downstream O2 from the Y pipe out of our donor truck as the bank 1 O2 Upstream sensor. Part number was the same, connector was different. I just spliced the connector onto the harness and plugged it in. The factory bank 1 upsteam was crushed, along with the connector.
I know I need to update the injector data, but the fact that this thing isn't even pushing 30 lb/hr through the MAF has me concerned. It won't light them up in first gear from a roll, either. Also, the TH350 wants to shift at 4500 so I manually shift it.
My biggest worry is my last outting, I hit 5800 RPM and the car felt like it hit a wall, but I believe it was from the mostly stock TH350 not being able to spin any higher. Still only 75% duty cycle on 25 lb/hr injectors.
Does anyone notice anything strange in the tune/log? I'm stumped on this one. No matter what I change, even when I start completely over on the tune (this is the third time), it seems to get to the point where it is now and then it levels out again.
Now, it won't spin the tires if you hammer it from a 5 MPH roll in first.
Setup is:
05 5.3
706 heads
Truck intake
DBC, stock throttle body.
MAF tune.
PAC 1218 Springs
226/232 .580/.590 115 LSA cam.
TH350
1 3/4" Long tubes
2.25 dual exhaust with flowmasters.
2800 stall truck converter that seems to be stalling around 2200.
99 4.8 ECU flashed for 1 bar OS MAF Enhanced tune.
TR5 plugs gapped at .040
There are some oddball situations here.
1. After the first fire, we swapped from the 99 4.8 21.8 lb/hr injectors to the 5.3s 25 lb/hr injectors after hitting 100% duty cycle. I have NOT updated the injector data.
2. I'm tuning without a wideband. I removed 30% fuel on Primary/Secondary VE tables from 0-800 RPM, 20% fuel from 1200-1600 RPM, 12% fuel at 2000 RPM. Added 10% at 3200, 15% at 3600-4200, 20% at 4600-5000, and 25% fuel from 5000+. This made it idle and cruise very well. I just need it 'close' for the time begin. It was originally started/tuned without the MAF plugged in.
3. I had to disable STFT/LTFT because it kept adding 50% to Bank 2. There is an exhaust leak between the header and exhaust.
4. I used the downstream O2 from the Y pipe out of our donor truck as the bank 1 O2 Upstream sensor. Part number was the same, connector was different. I just spliced the connector onto the harness and plugged it in. The factory bank 1 upsteam was crushed, along with the connector.
I know I need to update the injector data, but the fact that this thing isn't even pushing 30 lb/hr through the MAF has me concerned. It won't light them up in first gear from a roll, either. Also, the TH350 wants to shift at 4500 so I manually shift it.
My biggest worry is my last outting, I hit 5800 RPM and the car felt like it hit a wall, but I believe it was from the mostly stock TH350 not being able to spin any higher. Still only 75% duty cycle on 25 lb/hr injectors.
Does anyone notice anything strange in the tune/log? I'm stumped on this one. No matter what I change, even when I start completely over on the tune (this is the third time), it seems to get to the point where it is now and then it levels out again.
07-21-2016, 07:13 AM
#2
Restricted User
Thread Starter
Tried a retune. Still no power. 28 lb/hr on the MAF at 5900 RPM.
Low-end is really bad.
I would drop in a wideband, but the owner wants his car back in the next day or two and I wouldn't be able to have one delivered that quickly.
Low-end is really bad.
I would drop in a wideband, but the owner wants his car back in the next day or two and I wouldn't be able to have one delivered that quickly.